Acne vulgaris is a follicular skin disease that is characterized by the appearance of comedones, papules, nodules, and cysts. Comedones are hair follicles that are blocked with a keratin plug. Open comedones, those in which the keratin plug is visible, form “black heads” and closed comedones form “whiteheads” that often progress to inflamed papules, nodules, and cysts. The presence of bacteria in a follicle attracts white blood cells to the follicle, which can cause an inflammatory response seen as papules (red bumps), pustules, and nodules. Acne may be minor, where only a few comedones or papules are present, or it may be highly inflammatory and leave disfiguring scars. Improved methods of treating or ameliorating follicular skin diseases, such as acne vulgaris, are required.
The mechanism of one type of treatment described herein is through delivery of light absorbing particles in to the sebaceous follicles selectively followed by pulsed laser irradiation that causes selective heating. Cell death occurs primarily due to heat fixation or protein denaturation though some occurs via apoptosis and accidental cell death. It is desired to achieve a high level of injury in one single treatment but without collateral damage and side effects. Due to various reasons including limited delivery of the particles possible in one treatment, the injury is limited and may not lead to complete resolution of acne.
While a single treatment may be a complete treatment, there may be patients or treatment scenarios that would benefit from two or more treatments delivered in such a way as to further enhance the clinical outcome.